1. Field of the Invention
The present invention relates to a wrap around booster heater, and more specifically, the present invention relates to a wrap around booster heater for use with a dishwashing machine.
2. Description of the Prior Art
Generally, there are two types of dishwashing machines. Chemical dishwashing machines use high concentrations of chemicals to sanitize items, and high temperature dishwashing machines use high temperature water to sanitize items. Booster heaters are typically used in high temperature dishwashing machines to heat the water used in the dishwashing machines. The temperature of water flowing into a dishwashing machine is usually between 110 and 140xc2x0 F. In a single temperature dishwashing machine, the temperature of the water must be raised to approximately 165xc2x0 F. for both the wash cycle and the rinse cycle. In a dual temperature dishwashing machine, the temperature must be raised to at least 150xc2x0 F. for the wash water and to at least 180xc2x0 F. for the rinse water to comply with National Sanitation Foundation and the FDA requirements. A typical heating system used for high temperature sanitization requires a heating element that must be continually covered by water so the heating element will not become damaged. Therefore, a complete dumping of the water in the wash tank has not been possible in high temperature dishwashing machines. Prior art references have not shown complete dumping of the wash water in high temperature dishwashing machines.
U.S. Pat. No. 3,923,073 by Jacobs discloses means for preheating water of a domestic dishwasher by allowing the water to flow through a conduit before the water enters the dishwasher sump. Additional heat is supplied to the water entering the sump by means of a fill spout overlying the high end of a sloped trough and with the low end of the trough having an outlet communicating with the sump. A heating element is cradled within the trough so the water flowing through the trough heats to a predetermined temperature.
In U.S. Pat. No. 4,235,642 by Federighi et al., steam is used to heat the cold wash water directed to spray arms.
The use of a heat exchanger is disclosed in several patents. U.S. Pat. No. 4,326,551 by Voorhees discloses a heat recovery system including a heat exchanger in which fresh rinsing water flows in heat exchange relation with the excess washing solution from the sump before the rinsing water reaches the booster heater and the excess washing solution reaches the drain. Also disclosed is a booster heater separate from the dishwasher.
U.S. Pat. Nos. 4,529,032 and 4,531,572 by Molitor disclose methods and apparatus for recovery of waste energy. A heat exchanger is used to preheat incoming cold water for the hot water heater with the waste water suitable for discharge through the drain. The waste water is held in a holding tank and then passed through the heat exchanger during the rinse period, and heat is applied to the water in the hot water heater for the rinse water.
In U.S. Pat. No. 5,660,193 by Archer et al., warm, dirty cleaning liquid flows through the inner pipe of the heat exchanger into the drain channel in counterflow to the fresh water flowing in the outer pipe of the heat exchanger. Therefore, energy from the warm, dirty liquid is transferred to the fresh water in the heat exchanger.
Although U.S. Pat. No. 3,923,073 discloses a type of heat exchange, the heat exchange occurs from the trough to the water and not from one tank of water to another tank of water as in the present invention.
Unlike the prior art references, the present invention allows for complete dumping of the water contained in the wash tank of a high temperature dishwashing machine because the water in the wash tank is heated by the water in the rinse tank through convection, as described in more detail below.
A preferred embodiment heater tank assembly for use with a dishwashing machine includes a first tank, a second tank, and a heater. The first tank is capable of holding a first quantity of water at a first temperature and includes a plurality of side panels, an inlet, and an outlet. The second tank is capable of holding a second quantity of water at a second temperature and includes a plurality of side surfaces configured and arranged to surround the plurality of side panels of the first tank thereby allowing the second quantity of water to surround the plurality of side panels of the first tank. The second tank also includes an inlet and an outlet. The heater is in communication with the second quantity of water, and the heater raises the second temperature of the second quantity of water thereby also raising the first temperature of the first quantity of water by convection through the plurality of side panels of the first tank.
Another preferred embodiment heater tank assembly for use with a dishwashing machine includes a first tank, a second tank, and a heater. The first tank is capable of holding a first quantity of water and includes an inlet and an outlet. The second tank is capable of holding a second quantity of water and includes an inlet and an outlet, and the second quantity of water has a first temperature. The heater is in communication with the second quantity of water for raising the first temperature of the second quantity of water to a second temperature. The first quantity of water has a third temperature. The first tank includes a plurality of side panels and is configured and arranged to fit inside the second tank, whereby the second quantity of water surrounds the plurality of side panels of the first tank. The second temperature of the second quantity of water is higher than the third temperature of the first quantity of water. Therefore, the second quantity of water raises the third temperature of the first quantity of water to a fourth temperature by convection through the plurality of side panels thereby serving as a heater tank assembly.
In a preferred method of heating a first quantity of water of a first tank with a second quantity of water of a second tank in a dishwashing machine, a first tank including a plurality of side panels is placed inside a second tank configured and arranged to accept the first tank. The first tank is filled with a first quantity of water of a first temperature, and the second tank is filled with a second quantity of water of a second temperature. The second quantity of water contacts the plurality of side panels of the first tank. The second quantity of water is heated to a third temperature with a heater operatively connected to the second tank and submerged in the second quantity of water. The second quantity of water contacts the plurality of side panels of the first tank to heat the first quantity of water to a fourth temperature by convection through the plurality of side panels of the first tank.